It’s often said that the eyes are the windows to the soul. While there appears to be some truth to the saying, they’re also so much more than that. The eyes are quite literally our windows to the outside world. They allow us to interact with our surroundings in a meaningful way, and to navigate the everyday with safety and ease.
The gift of sight is one that we generally take for granted - it’s only when it’s snatched away from us that we notice the innumerable ways in which eyesight enriches our lives. Vision loss or deterioration can be absolutely devastating, both from a practical standpoint and an emotional one. For this reason, doctors and scientists across many fields have dedicated their careers to understanding vision and the afflictions that affect it in the hopes of helping people preserve or regain their eyesight, and ultimately, their independence.
Among the emerging areas of research dedicated to eye health and vision restoration is red light therapy. While it’s been around for a while, and is gaining quite a bit of traction as a safe and effective treatment for a variety of ailments, it’s only recently that eye experts have set their sights on therapeutic effects of red light therapy for eye health.
What Is Red Light Therapy?
Red light therapy, also called photobiomodulation or low-level light therapy, is a therapeutic technique in which light-emitting diodes (LED) diffuse red and near-infrared (NIR) wavelengths of light through the skin into the cells. It works by activating your body’s own mitochondrial response to create energy and boost the functioning of your tissues and organs. Sounds like a mouthful? Let’s break it down.
Mitochondria are the little energy factories within your cells that are responsible for cellular respiration, which is the process of converting chemical energy from oxygen molecules and nutrients into adenosine triphosphate (ATP). ATP is your body’s “energy currency”, which travels to every organ and tissue in your body, allowing them to perform their various functions. ATP synthesis is the end result of the mitochondrial respiratory chain, or mitochondrial electron transport chain (METC). (It’s a rather complex process; for a simple yet thorough explanation of how it works, check out this article by ThoughtCo.)
The wide-ranging benefits of red light therapy were first discovered accidentally in 1967 by Hungarian physicist Dr. Endre Mester. He’d been conducting a study using ruby lasers to determine the effect of laser exposure on cancerous tumors in mice. While he did not observe any changes in the tumors, he did notice something unexpected: the mice who’d undergone laser treatment showed faster hair regrowth and wound healing than the control group.
Thus began decades of research on red light therapy, uncovering dozens of benefits affecting the body from head to toe. Today, the long - and growing - list of benefits associated with red light therapy includes:
- Skin rejuvenation, wound, and scar healing;
- Muscle growth, performance, and recovery;
- Weight loss;
- Hair growth;
- Cognitive health;
- Immune health;
- Hormones and sex drive;
- Pain and inflammation;
- Mental health and depression;
- Sleep disturbances;
- Oral and dental health;
- And, of course, eye health.
But what are the underlying mechanisms through which red light therapy affects eye health? Here’s a quick overview.
How Does Red Light Therapy Affect Eye Health?
By increasing mitochondrial function, red light therapy protects against excitotoxic cell death (death of neurons). It also protects against inhibition of the METC. When proper functioning of the METC is inhibited, it causes oxidative stress by turning leftover oxygen into reactive oxygen species (ROS). ROS are known to cause damage to lipids, proteins, DNA, and RNA. They can also damage the METC itself, which leads to increased ROS, and so on. This cycle is a normal part of aging, and it’s why eyesight tends to deteriorate as we get older.
Red light therapy also has well-documented antiinflammatory effects. More specifically, it appears to suppress the expression of proinflammatory cytokines. These are proteins that signal the body to go into reaction mode to fight illness or infection. While this is a good thing to an extent, inflammation overdrive can have negative effects, including in this case, damage to neural tissue, which can affect eye health.
Red light therapy is also known to improve circulation. Improper blood flow to the eye and optic nerve can increase one’s susceptibility to ocular illness. Decreased blood flow is associated with a number of eye conditions, including glaucoma, macular degeneration, and retinitis pigmentosa, to name a few.   
For further reading, this article explores in an in-depth fashion the possible underlying mechanisms of red light therapy’s beneficial effects on eye health.
Another reason why the eyes are particularly affected by mitochondrial dysfunction is that the eye, specifically the retina, has the highest concentration of mitochondria in the body. It also has the highest metabolic demand in the body, meaning that the mitochondria are not just there for decoration, but to provide the high levels of energy that the eyes require to function well. 
This abundance of mitochondria and high demand for energy is precisely why the eyes respond so well to red light therapy treatment. Let’s take a look at some common eye conditions that can be treated with red light therapy.
What Eye Conditions Can Red Light Therapy Treat?
There may be hope yet for those who suffer from various eye disorders, in the form of safe, non-invasive - and affordable - red light therapy treatment.
We’ll be referring to visual acuity (VA) quite a bit, so let’s quickly go over what it means. VA refers to one’s ability to see objects sharply. The standard of measurement for this is 20 feet. A vision test measures how clearly you can see an object that’s 20 feet away compared to a person with normal vision. 20/20 vision means that you see objects with the same sharpness as a normally-sighted person from 20 feet away. 20/50 vision, for instance, means that you can see an object sharply at a 20-foot distance that a person with normal vision can see from 50 feet away.
Age-related macular degeneration is the most common eye disorder in people over 50, and is the leading cause of blindness in developed countries. It occurs when the part of the retina responsible for clear vision, the macula, is damaged. Central vision becomes blurred or reduced, meaning you’ll have trouble making out details in your direct line of sight, while your peripheral vision may remain intact.
Recent studies on red light therapy for AMD have shown encouraging data. One early study from 2008 found increased visual acuity in patients with AMD who were treated with red light therapy compared to control subjects. Results were similar for patients both with and without cataracts. 
A more recent study from 2018 followed 33 subjects over the age of 60, all with varying degrees of AMD. Of those subjects, 11 were randomly selected to receive six three-minute laser treatments, administered every second day, while the remaining 22 underwent a placebo treatment. Subjects were then monitored for a period of five years. While researchers noted no improvement in the placebo group, the treatment group showed significant improvement. This improvement was maintained after five years, indicating that red light therapy can have long-term benefits for AMD sufferers. 
How does it work? It’s not entirely clear, but according to recent studies, red light therapy may improve AMD by acting on the retinal pigment epithelium. RPE is a thin layer of cells that, among other things, protects the retina and regulates the nutrient and waste comings and goings.   A 2019 study found that oxidative stress can trigger degeneration in both RPE and photoreceptors in AMD. 
Diabetic retinopathy (DR) occurs when high blood sugar levels associated with diabetes cause damage to the blood vessels in the retina, resulting in vision loss. It has been found that the macula is thicker in patients with DR than in healthy subjects. 
In a 2014 study, researchers studied the effects of photobiomodulation on 4 subjects with DR. For each subject, they treated only one eye for 80 seconds, twice daily for 2 to 9 months. The other eye served as control and received no treatment. They found a 20% decrease in macular thickness in the eyes that received red light therapy treatment. The untreated eye, in contrast, saw an average increase in macular thickness of 3%. 
A number of animal studies and in vitro (using cultured retinal cells) studies have also been conducted with results supporting the findings above.    These and other studies show that red light therapy improves DR through various direct and indirect mechanisms. For instance, RLT inhibits the degeneration of retinal capillaries as well as leakage caused by diabetes.
Also known as lazy eye, amblyopia affects an estimated 1.75% of the population.  It occurs when the brain ceases to recognize signals from the affected eye, causing the healthy eye to work harder and, consequently the affected eye to weaken further. The main causes of amblyopia are ametropia (issues involving refraction, i.e. the inability for light to properly focus on the retina, causing blurred vision in the weaker eye) and strabismus (misalignment of the eyes causing the brain to eventually stop recognizing the vision of the weaker eye).
There is a critical window for treatment, usually within the first decade of life. If left untreated past this period, the damage is generally considered to be permanent. Red light therapy, however, offers some hope for adolescents and adults with the condition.
A 2011 study was conducted on 178 patients between 13 and 72 years of age. Of these patients, approximately half had amblyopia caused by ametropia, while the other half had strabismus as the cause. Red light therapy treatment was given to 231 eyes, while the control group consisting of 20 eyes of 20 different patients received a mock treatment. Treatment was administered 3-4 times over a period of 2 weeks. The treated eyes with ametropia saw a 91% improvement of visual acuity, while those with strabismus improved by 89%. The control group recorded no significant improvement. A 6-month follow-up showed no deterioration of visual acuity in the treated eyes. 
While the mechanisms are as yet unclear, increased cellular metabolism is a likely factor. It also appears that synaptogenesis, or the formation of new synapses, may play a role. A synapse is the gap between neurons that allows for electrical signals to pass between them. It’s how your body communicates with your central nervous system and vice versa. Increased synaptogenesis could improve communication between the weaker eye and the brain.
Retinitis pigmentosa is a genetic condition that affects the retina’s ability to respond to light, causing loss of vision over time. It can cause impaired night vision, peripheral vision, or central vision, as well as problems with color vision. While it rarely causes complete blindness, RP can make daily tasks, such as reading, driving, or even walking, difficult and in some cases impossible.
Recent studies have shown photobiomodulation to be effective in countering the progression of RP in animals.   And recent human studies are showing even more promise.
A 2014 study observed the effects of red light therapy on a single patient with RP. The 55-year-old patient had a visual acuity of 20/50 in both eyes and a central visual field of 5 degrees (for context, the average person has a visual field of 170 degrees; less than 20 degrees is considered legally blind). He received 40 seconds of irradiation to both eyes twice a week for 2 weeks. Post-treatment, the patient’s vision was measured at 20/20, and his peripheral vision was restored as well. The only remaining dysfunction was a mid-peripheral circular scotoma (blind spot). The effects lasted 5 years, after which the patient’s vision returned to its pretreatment state. He underwent another successful round of treatment, however, and subsequently continued with treatments as needed, with no deleterious effects. 
A study conducted the following year had 14 RP patients undergo red light therapy treatment for 3 minutes every 2 days for a total of 20 days. Researchers found significant improvement in visual acuity lasting for the entire 3-year follow-up period. In contrast to the other study, this group did see an improvement in mid-peripheral circular scotoma. This study also reported no side effects. 
While more research is certainly needed, the positive results combined with a lack of side effects indicates that red light therapy has extreme potential as an effective and long-lasting treatment for PR.
One of the leading causes of blindness in people over 60, glaucoma is a series of eye conditions that affect the optic nerve. This progressive nerve damage eventually results in blind spots in the visual field. While experts are not yet clear on why, it seems this optic nerve degeneration is caused by increased pressure in the eye due to buildup and improper drainage of aqueous humor, the fluid that fills the eye. AH normally drains at the juncture of the iris and the cornea, through a tissue called the trabecular meshwork.
The various types of the condition include open-angle glaucoma (the angle at the iris-cornea juncture is open but the meshwork has a blockage), angle-closure glaucoma (the iris has a bulge that blocks the drainage angle), normal-tension glaucoma (optic nerve damage with no apparent eye pressure), and pigmentary glaucoma (pigment granules from the iris accumulate in the drainage angle, causing blockage).
While there are currently no studies that have directly investigated the effect of red light therapy on glaucoma, there is mounting evidence that mitochondrial dysfunction may play an important role. The hypothesis is that the reduced energy caused by age-related mitochondrial dysfunction can inhibit the repair of retinal ganglion cells (RGC), making them susceptible to apoptosis (cell death). RGCs capture the images you see and send them to your brain. Once they die, they are not replaced. The key to improving glaucoma outcomes, it would then seem, is to find ways to prevent RGC death.    
Given that red light therapy’s primary effect is increased ATP production at the mitochondrial level, it’s looking increasingly likely that it would have a positive effect on glaucoma, especially considering the sheer number of mitochondria present in the retina. While more research must be conducted to confirm a direct effect of photobiomodulation on glaucoma, red light therapy’s safety profile and well-documented lack of side effects make it a viable, low-risk treatment option in the meantime.
Is Red Light Therapy Safe for the Eyes?
Thousands of studies have been conducted to date on the various benefits of red light therapy. Besides a growing mountain of evidence confirming its efficacy at treating a variety of issues and ailments, there is also overwhelming evidence of its overall safety.
However, you might be a bit more reluctant to expose your eyes to direct light - much more so than, say, your skin - and with good reason. Certain wavelengths can indeed cause damage to the eyes. UV light has long been known to cause extensive eye damage, prompting the widespread use of sunglasses. Recent research has shown that blue light may have a negative effect on the mitochondria of retinal ganglion cells, leading to increased RGC death. This has important implications for glaucoma and possibly other eye conditions. 
But what of red and near-infrared (NIR) light? As with any light, there is potential for photoreceptor damage (after all, most red light therapy devices come equipped with protective eyewear). However, treating the eyes with red light therapy can be done safely and without damage to the eye. It comes down to two factors: length of exposure, and wavelength.
Length of exposure
As you may have noted, all studies involving red light therapy and eye health kept exposure to a minimum, generally between 30 and 90 seconds at a time, with a day or two break in between treatments. In most studies, patients saw long-lasting effects after approximately two weeks of treatment.
Light is essentially a series of electromagnetic waves, some visible and some not. In fact, visible light makes up only a fraction of the spectrum of light. Red light finds itself at one end of the visible light spectrum, and is generally measured at around 600-700 nanometers. Just beyond red light is NIR, which is invisible to the naked eye. It measures anywhere between about 780nm and 1mm.
The majority of studies conducted on red light therapy and eye health use red light at 670nm. This wavelength is considered to be the most effective in terms of protective effects. Many studies have also been conducted using NIR with similar positive effects.  However, one rat study on the protective effects of red light therapy on retinal degeneration found that while 670nm was effective, 830nm produced no protective effects. 
Furthermore, a 1984 study found a possible link between prolonged exposure to NIR light and the development of cataracts over time.  However, this study involved glass, iron, and steel workers who spend a great deal of their working life exposed to NIR light. Red light therapy, on the other hand, requires very limited exposure to be beneficial, with sessions of 30-90 seconds every few days for a period of approximately 2 weeks.
Further research may be needed to determine with certainty whether short-term exposure to NIR light carries the same potential risk, however unlikely. In the meantime, your best bet for eye health is to stick to the sweet spot: red light at approximately 670nm.
The Good News About At-Home Red Light Therapy and Eye Health
Rouge red light therapy devices contain two types of LED lights. One emits red light at 660nm while the other effuses NIR light at 850nm. In fact, you’ll notice that it looks like only some of the lights on the panel are on. These are the red lights, which are visible to the naked eye; you simply can’t see the NIR light.
The good news is that you can set your Rouge red light therapy panel to only emit red light without NIR, and vice versa. This allows you to use solely red light for eye treatment. And don’t worry about keeping your eyes open: red light works just as effectively through the eyelid. In fact, this is why it’s important to wear the protective eyewear provided with your device for any treatment not specifically targeting the eyes.
As always, we urge you to consult your healthcare provider before beginning any treatment regimen. Your ophthalmologist may be able to help you design a treatment plan that is most beneficial to your specific needs, and can monitor your progress to ensure all safety measures are taken.
How Do I Get Started?
You’ve made it through this article. Congratulations, you’re halfway there!
Rouge’s Tabletop and Nano Portable Red Light Therapy Panels are the perfect size for any and all eye-related issues. If you’re looking for the full-body treatment, however, our larger devices offer the same eye-health benefits, and can help you with a host of other issues, including pain and inflammation, skin rejuvenation and wound healing, athletic performance and weight loss, and plenty more! Check out our brief overview of the many benefits of red light therapy here.
Talk to your eye doctor about red light therapy today, and get started on the path to clearer, better vision.
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